Understanding Layer Composition in TypeScript

Wrapping my head around layer composition—I think I'm close but I'm trying to understand the benefits of the example merging

ConfigLive

ConfigLive

and

LoggerLive

LoggerLive

to build an

AppConfigLive

AppConfigLive

const AppConfigLive = Layer.merge(ConfigLive, LoggerLive)
 
const MainLive = DatabaseLive.pipe(
  // provides the config and logger to the database
  Layer.provide(AppConfigLive),
  // provides the config to AppConfigLive
  Layer.provide(ConfigLive)
)

const AppConfigLive = Layer.merge(ConfigLive, LoggerLive)
 
const MainLive = DatabaseLive.pipe(
  // provides the config and logger to the database
  Layer.provide(AppConfigLive),
  // provides the config to AppConfigLive
  Layer.provide(ConfigLive)
)

What is the benefit here over doing:

const MainLive = DatabaseLive.pipe(
  Layer.provide(LoggerLive),
  Layer.provide(ConfigLive),
)

const MainLive = DatabaseLive.pipe(
  Layer.provide(LoggerLive),
  Layer.provide(ConfigLive),
)

I'm guessing that the compositional benefits due to the type signature of

AppConfigLive

AppConfigLive

becomes more obvious in a larger example, but having a bit of trouble making that jump with the current docs. Would appreciate any clarity!

Effect Community•2y ago

Stoids

Understanding Layer Composition in TypeScript

Wrapping my head around layer composition—I think I'm close but I'm trying to understand the benefits of the example merging

ConfigLive

ConfigLive

and

LoggerLive

LoggerLive

to build an

AppConfigLive

AppConfigLive

const AppConfigLive = Layer.merge(ConfigLive, LoggerLive)
 
const MainLive = DatabaseLive.pipe(
  // provides the config and logger to the database
  Layer.provide(AppConfigLive),
  // provides the config to AppConfigLive
  Layer.provide(ConfigLive)
)

const AppConfigLive = Layer.merge(ConfigLive, LoggerLive)
 
const MainLive = DatabaseLive.pipe(
  // provides the config and logger to the database
  Layer.provide(AppConfigLive),
  // provides the config to AppConfigLive
  Layer.provide(ConfigLive)
)

What is the benefit here over doing:

const MainLive = DatabaseLive.pipe(
  Layer.provide(LoggerLive),
  Layer.provide(ConfigLive),
)

const MainLive = DatabaseLive.pipe(
  Layer.provide(LoggerLive),
  Layer.provide(ConfigLive),
)

I'm guessing that the compositional benefits due to the type signature of

AppConfigLive

AppConfigLive

becomes more obvious in a larger example, but having a bit of trouble making that jump with the current docs. Would appreciate any clarity!

Understanding Layer Composition in TypeScript

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